Bending jig



Patented Aug. 20, 1940 UNETED STA'liZii EPAENT I FFEUE 2 Claims.

The present invention relates" to bending devices and more particularly to a bending jig to facilitate manual bending of strap and bar stock and the like.

The principal object of the invention is topro-' vide a jig by which metal stock may be readily bent to any desired curvature, and to this end the invention comprises the jig hereinafter de scribed and particularly defined in. the claims.

In the accompanying drawing Fig. 1 is a side elevation of a jig according to the present invention; Fig. 2 is a plan view of the jig; and Fig. 3 is a sectional elevation of a preferred mounting device for the jig in accordance with another feature of the invention.

The jig shown in Figs. 1 and 2 comprises a plate 4 provided with an upstanding pin 6 secured therein. The pin is preferably about one-half inch in diameter, which is small enough to permit bending of ordinary stock to the minimum radius usually required, and sufficiently strong to resist the forces required to bend stock of considerable thickness. I

Cooperating with the bending pin 6 is a backing piece 8 cylindrical in shape and of considerably larger diameter thanthe pin. The backing piece 8 is adjustably mounted on a pivot pin Hi which is secured in the plate 4 and which passes through an eccentric hole in the backing piece. The backing piece may. be held in one of a number of adjustable positions. with relation to the bending pin by means of a locking pin' I2 which extends downwardly from the backing piece and is adapted to enter one of a series of accurately spaced holes 14 in the plate 4. Inpractice the backing piece is set in such position that the space between the backing piece and the bending pin is approximately equal to oronly slightly greater than the thickness of the stock. In the full line 40 position shown in Fig. 2 the backing piece is set for the minimum thickness of stock. For greater stock thicknesses the backing piece is set so that the locking pin engages a different hole I 4 in the plate, as indicated by the dot-and-dash lines. For usual bending work, the backing piece may be adjusted to accommodate stock between and inch in thickness.

The backing piece having been set in the proper position with respect to the pin, the stock is inserted and is manually pulled against the bending pin until the desired curve is obtained. It is well known that an accurate bend, particularly of short radius, cannot be obtained by bending the stock arcund a single abutment. The backing piece properly grips and backs up the stock so that the desired curve can be readily obtained. For making ornamental devices, such as wroughtiron lamp stands and the like, the operator may easily slide the stock through the jig and bend it to the proper curves at the desired places with assurance that the stock will retain its shape after removal fromthe jig.

The jig shown in Figs. 1 and 2 is provided with a depending portion it to permit clamping of the jig in a vise. Where a considerable amount of metal bending is being done, however, the mount- I ing device shown in Fig. 3 may be employed. This comprises a metal base it which may be permanently bolted to a bench. The base is provided with a central opening 20 of regular shape I conforming to the depending portion l6 of the jig. The portion l8 and the opening 20 are preferably square, so that the jig may be set in any one of the four possible positions in'the base. The portion 56 and the opening in the base should be formed with suficient accuracy so that the jig may be tightly held in the base without danger of its being pulled out under the forces necessarily applied. during a bending operation. To accomplish this result a base of considerable height is not required, and the base may be made of small height so that it will not interfere with other work at the bench when the jig is removed.

The invention having been thus described, what is claimed is:

l. A bending jig comprising a plate, a pin upstanding from the plate, a backing piece of materially larger diameter than the pin, an eccentric pivot for the backing piece to permit adjustment of the space between the backing piece and the pin, and a locking member carried by the backing piece, the plate having a series of accurately spaced holes to receive the locking member and thereby to hold the backing piece in adjusted position.

2. A bending jig comprising a plate, a. bending pin upstanding from the plate, a cylindrical back ing piece, a pivot pin on which the backing piece is eccentrically mounted to vary the spacing between the backing piece and the bending pin, and a locking pin carried by the backing piece, the plate having a series of accurately spaced holes to receive the bending pin to hold the backing piece in a selected position with respect to the bending pin.

JOHN B. BUTLER. 

